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I am using a USB-soundcard to record on my raspberry pi and it records fine and the recorded sound is great, however if I am playing any other sound clip (through the audio output port on the raspberry pi and not my USB) the recorded sound is very bad like chunks of it are not recorded. Any ideas where this problem is coming from and how to solve it? Maybe a power problem?

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    I would probably say that it is because of a lack of processing power. You're recording and playing audio at the same time, so you've got two relatively heavy things going on (at least for something like the RPi.) Something will end up suffering. However, it could be code. That was the issue on the Raspberry Pi Forums for an issue very similar to yours. Could you post what software method(s) you are using to get and play audio? (Eg. Custom Programming - Python/C/C++/Java, pre-programmed software, etc.) – RPiAwesomeness May 8 '14 at 23:02
  • I am using python to send and receive audio from the pi to an android application. If I made the same code on the raspberry pi only receive the sound is great and if i make it only send then no problem too.. the problem only occurs when I am running the two threads together(sending and receiving) – user14734 May 13 '14 at 21:29
  • Also when I use the raspi camera to send images to the android application it makes things far worse – user14734 May 13 '14 at 21:39
  • Did you read the Raspberry Pi Forum post I linked to? – RPiAwesomeness May 13 '14 at 22:26
  • Yes and it didn't help solve the problem – user14734 May 18 '14 at 2:42
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Their are two reasons for this, and only one is fixable.

CASE 1

Your Pi is not getting enough power. Make sure you have a short and thick cord, do not try to use a cheap thin and long one, like the phone charger cords. If you have a lot of usb devices plugged in, you may want to invest in a powered usb hub. Finally, the Pi needs about 2 amps to work comfortably, but the more things you have plugged in and the more work it has to do, the more amps it will need, personally, I use a 5.5V 5A power source, and my external sound card records while outputting fine.

CASE 2

Your external sound card may be the source of the problem. Make sure all of the connections are fine and nothing is blatantly broken. If Case 1 is not correct and you believe your sound card is working fine then you should purchase another card, just a cheap one, to make sure it is not the Pi's fault. I am using the one here: http://www.amazon.com/gp/product/B00M3UWE3Q?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00 it is only about $3 and for what I needed it works great.

Good luck to you!

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I agree it's likley a lack of CPU cycles .. the Pi sound output is essentially 'bit banging' and USB is 'byte at a time' so both use a ton of CPU cycles = no doubt the Pi gives sound out priority over USB (USB can 'retry') so I would expect the recording to be the one to fail ..

The way to check is to 'over-clock' the Pi and see if the quality improves ..

A power problem is just possible (although sound out takes very little additional power) - and the fact that your USB device works perfectly when you are NOT outputting audio from the Pi proves it's working fine (although that's not to say it's USB 'loading' isn't 'excessive' and another device with a different driver might work better)

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